NOAA: 2-Week Dry Spell For California… At Least…

WEEK TWO OUTLOOK...Feb 2nd-8th...Issued 3pm 1/25 
   
  Large scale pattern going into the beginning of February continues  
  to point towards an extended period of dryness for the Sierra and  
  western Nevada.  
   
  Long range ensembles and short range climate models continue to show  
  an amplified ridge of high pressure building off the West Coast  
  and into Alaska for the start of February as troughing deepens  
  into the Midwest and northeast states. While the ridge over the  
  West amplifies, it is forecast to build a strong high pressure  
  anomaly into the Arctic which could cause significant atmospheric  
  blocking in the lower latitudes, potentially helping to keep the  
  ridge of high pressure locked in place for an extended period of  
  time.  
   
  Another potentially significant factor is a robust Madden-Julian  
  Oscillation event currently over southeast Asia that is forecast  
  to move into the West Pacific in early February. Forecast models  
  are in relatively good agreement with this event, increasing  
  forecast confidence in the upcoming pattern. This MJO event is  
  forecast to teleconnect well with North America; basically this  
  means that the MJO event in the West Pacific Ocean will likely  
  influence the pattern over the U.S. during the first couple weeks  
  of February. The affect from this type of event is usually to  
  enhance troughing in the East and ridging in the Western U.S.  
   
  The developing pattern is very similar to the pattern that  
  developed over the U.S. during December and brought near record  
  dryness to the region for the end of 2017. As the high pressure  
  builds off the coast over the next week or two, it will still be  
  possible for slider type storms to drop into the region from the  
  north, but these storms tend to be pretty dry. The trough in the  
  east will make it difficult for the high pressure along the coast  
  to retrograde far enough west to allow stronger storms in from the 
  Gulf of Alaska. The other way we can break out of this type of  
  pattern is for the amplified high pressure to be undercut by a  
  strong incoming Pacific jet, but there are not any good signals  
  for that pattern as of now. Either way, this type of pattern,  
  especially in recent years, has shown a resilience that makes it  
  tough to break out of. 
   
  At this point no one can say how long it will be before 
  significant precipitation events return the region, but the way  
  the pattern is building in it looks like it could be a while.  
  This doesn`t mean winter is over here in the Sierra, but we might  
  have to wait a while before it returns. -Zach